In refrigerating storehouses, inner walls are covered with frost, which is formed from moisture contained in air and objects stored in the storehouses. If such frost is left unremoved, the walls are gradually covered with ice, resulting in a considerable drop in thermal efficiency of the refrigerating storehouses. Therefore, frost and ice must be removed periodically. In order to remove frost and ice, objects in a refrigerating storehouse must firstly be moved to the outside while refrigeration is temporarily stopped, and the defrosting operation is performed manually.
In order to solve the above problems, there have heretofore been proposed chemical compositions for preventing icing; for example, a thickening organic composition formed from water-miscible organic liquid with alumina (Patent Document 1). However, such an organic composition is not suited for use in a refrigerator for storing food, since undesired contact of alumina with food may occur. Another known composition is formed from ethyl alcohol with bentonite, acid clay, abrasive powder, and talc (Patent Document 2). This alcohol-based composition encounters difficulty in maintaining anti-frost effect, since ethyl alcohol readily evaporates. In addition, the aforementioned compositions disclosed in Patent Documents 1 and 2 are formed of a liquid anti-freeze thickened by specific solid additives, and have a problem in that a long-term stable anti-freeze effect cannot be attained due to poor stability of base oil, separation of anti-freeze liquid from the compositions, and a change in consistency of the compositions. Thus, these compositions are different from the composition of the present invention assuming a grease-like consistency (hereinafter referred to as greasy composition).
Still another disclosed composition is a gel material which is formed by mixing an alcohol such as ethylene glycol or propylene glycol with a thickener such as hydroxymethyl cellulose (Patent Document 3) and which exhibits its anti-freeze effect only by the freezing-point-depressing action of the alcohol and other ingredients. Therefore, the composition can be applied to short-term prevention of icing of a front window pane of an automobile but may exhibit unsatisfactory defrosting and anti-freezing effects over a long period of time under severe circumstances found in refrigerating storehouses. Besides the aforementioned compositions, a variety of chemical compositions mainly for melting snow on road surfaces and anti-icing roads have also been proposed. For example, Patent Document 4 discloses an anti-freeze containing a mixture of a C1 to C10 carboxylic acid salt and a water-soluble polyhydric alcohol, a water-soluble polymer, and an inorganic substance. If these anti-freezes are employed for defrosting inner walls of a refrigerating storehouse, their performance must be maintained for at least half a year. However, when actually applied onto a vertical surface, these anti-freezes for the application to road surfaces problematically fall within a short period.    [Patent Document 1] Japanese Kohyo (PCT) Patent Publication No. 1996-506130    [Patent Document 2] Japanese Patent No. 144709    [Patent Document 3] Japanese Patent Application Laid-Open (kokai) No. 2000-328047    [Patent Document 4] Japanese Patent Application Laid-Open (kokai) No. 10-251622